Ion implantation is a semiconductor device fabrication technique that may be used to change the electronic properties of a semiconductor wafer by adding specific dopants to the wafer. More particularly, in conventional ion implantation, a desired ion species to be implanted into the wafer may be ionized, accelerated to a predetermined kinetic energy, and directed as an ion beam towards the surface of a semiconductor wafer loaded in an ion implantation target chamber. Based on the predetermined kinetic energy, the desired ion species may penetrate into the semiconductor wafer to a certain depth. As such, ions may be embedded (i.e., implanted) into the semiconductor wafer, which may thereby alter the electrical properties of the semiconductor wafer.
In some materials, ion implantation at relatively high temperatures (for example, up to 1800° C.) may provide several advantages, such as damage recovery, structure modification, increased chemical reaction, and/or enhanced diffusion of the implanted element. For example, high-temperature ion implantation into a silicon carbide (SiC) substrate may provide improved activation efficiency of the implanted species, lower sheet resistance of the implanted layer, higher carrier mobility, and/or reduced damage to the silicon carbide substrate as compared to ion implantation at room temperature. As ion implantation is typically performed in a vacuum, several methods have been used to provide the relatively high temperatures. For instance, resistive heaters, such as tungsten wire and/or graphite film, may be used to provide such increased temperatures in an ion implantation target chamber. Also, tungsten lamps may be used to increase temperatures in the ion implantation target chamber.
In conventional semiconductor wafer manufacturing, the semiconductor wafers may be stored on wafer holding plates in a load lock chamber adjacent to the ion implantation chamber. Each wafer holding plate may be individually loaded from the load lock chamber into the ion implantation chamber for ion implantation into the semiconductor wafer(s) thereon, and may be unloaded back into the load lock chamber when the ion implantation is completed. As such, it may be necessary to open the ion implantation target chamber to unload the current wafer plate and load the next wafer plate into the chamber. More particularly, the chamber pressure and temperature may be ramped down to unload the current wafer plate and load the next wafer plate, then ramped back up to a desired pressure and/or temperature for implantation into the semiconductor wafer on the next wafer plate. This may be a time-consuming process, which may affect throughput time for the ion implantation system.
Also, in conventional ion implantation systems, quartz wafer holding plates may be used to hold the semiconductor wafers for ion implantation at relatively high temperatures. The semiconductor wafers may be attached to quartz wafer holding plates by clips created from quartz rods. However, the quartz clips may be attached to the quartz plate by melting the quartz plate, which may result in warping of the quartz plate. The quartz clips may also mask a significant area of the semiconductor wafer to be implanted.